1. Field of the Invention
The present invention relates to an ink discharge head for discharging a recording liquid used for an ink jet recording system, and manufacturing method thereof.
2. Description of the Related Art
Conventionally, an ink jet recording system in which an ink droplet is discharged and the ink droplet is made to adhere to a print medium, such as paper, is known. In this ink jet recording system, the noise during recording operation is small, high-speed recording operation is possible, and it is possible to miniaturize the ink discharge head itself. Thus, this ink jet recording system is a recording system which is easy to miniaturize.
As a method of discharging an ink droplet, there are a method of controlling an applied voltage to a piezoelectric element and discharging an ink droplet using a mechanical change of an element, and a method of bubbling ink by a heat generating element, and discharging an ink droplet, utilizing the air bubble expansion at that time.
With the recent development of ink jet recording technique, higher density and higher definition are required in an ink jet recording technique. In order to satisfy this requirement, for example, a method for manufacturing a nozzle tip is suggested (Japanese Patent Application Laid-Open No. H6-286149) in which a nozzle layer is formed using a resin material capable of being patterned by photolithography, on a silicon wafer in which heat generating elements and a drive circuit are provided in advance.
In this manufacturing method, the resin layer for formation of ink flow passages is formed in advance in a predetermined pattern, using a resin material capable of being removed with a solvent. Then, a nozzle tip is formed by covering the top of the pattern of the resin layer for formation of ink flow passages with a coating resin layer, such as epoxy resin, processing nozzles in a coating resin layer, and removing the resin layer for formation of ink flow passages with a solvent.
Meanwhile, in the ink jet recording technique, higher recording operation speed is also required. A method of realizing higher speed includes, for example, increasing the dimensions of the ink discharge head, thereby increasing the number of discharge ports for ink droplets, in the manufacturing method of Japanese Patent Application Laid-Open No. H6-286149. It is thereby possible to increase the quantity of ink droplets capable of being discharged per unit period, and to achieve higher recording operation speed.
However, since the volume of the coating resin layer which becomes the nozzle layer increases in a case where the ink discharge head is lengthened, the stress generated when the coating resin layer is cured will increase. For this reason, the deformation of the ink discharge head itself will increase with the lengthening of the ink discharge head.
Additionally, in a case where the mounting of fixing the ink discharge head to a head support with an adhesive for mounting is performed in a state where the deformation of the ink discharge head is large, a tensile stress is generated in the ink discharge head due to the stress generated when the adhesive for mounting is cured. Also, since the direction in which the stress caused by the adhesive for mounting is generated is a direction opposite to the stress which acts on the coating resin layer, a larger shear stress is generated at the interface between the coating resin layer and the substrate. For this reason, peeling-off may occur at the interface between the coating resin layer and the substrate.
In a case where peeling-off has occurred at the interface between the coating resin layer and the substrate, ink permeates from this interface. Then, when the ink which has permeated arrives at the drive circuit on the substrate, this becomes the primary factor corroding the drive circuit and degrading the reliability of the quality of a product. Also, in a case where such peeling-off has occurred in a manufacturing process, this becomes a cause of a reduced production yield and increased manufacturing costs.